This invention relates to the technical field of a light diffusing plate and a display apparatus, more particularly to a diffusion plate capable of realizing a liquid crystal display which has a wide viewing angle and represents a high contrast image, a liquid crystal display device utilizing the light diffusing plate and an image display apparatus having a matrix structure.
In recent years, with the increasing popularity of a word processor, a personal computer and the like, various image display apparatuses have been developed to be in use of representing an image.
An image display apparatus generally comprises a display device representing an image light converted from image information electrical signals, a driver circuit for driving this display device and a power supply for supplying electric power to this driver circuit. In accordance with an optical system of displaying or a driving system of display device, there exist various image display devices; however, a cathode ray tube (hereinafter referred to simply as xe2x80x9cCRTxe2x80x9d) display is the most popular. For example, in the medical field such as ultrasonic diagnosis, CT (computer tomogaphy) diagnosis, MRI (magnetic resonance imaging) diagnosis and the like, a monochromatic CRT display has been used. The monochromatic CRT display has no digital matrix structure so that it can obtain a smooth and natural image.
The liquid crystal display (hereinafter referred to simply as xe2x80x9cLCDxe2x80x9d) has advantages such as easy downsizability, thinness, light weight and the like so that it has recently been used in various fields. Particularly, as a display of a word processor or a computer, the LCD is rapidly expanding its usage. The LCD is under consideration for the application of a monitor for medical diagnosis device such as an ultrasonic diagnosis device, a CRT diagnosis device, an MRI diagnosis device or the like in which the CRT display has conventionally been primarily used.
While the LCD has many advantages such as easy downsizable, thinness, light weight and the like, as described above, it also has disadvantages that viewing angle characteristics are poor (narrow viewing angle), namely, the image can be seen differently since the contrast ratio of an image may sharply be decreased or an image gradation may be reversed depending on a viewing direction or angle. Therefore, there exists a problem that the image can not be appropriately viewed depending on a viewer""s position or the like. Particularly, in the above-described medical application or the like, diagnosis is performed based on image density so that the image having a high contrast ratio is required and inappropriate recognition of the image would cause wrong diagnosis, inconsistency in the results of diagnoses or the like. Therefore, the image having the high contrast ratio displayed over a wide viewing angle is required in particular. Moreover, it is more problematic in the monitor of medical application that the represented image is generally monochromatic so that the image contrast which is dependent on the viewing angle decreases sharply.
As the LCD for a wide viewing angle, an LCD of In-Plane Switching (hereinafter referred to simply as xe2x80x9cIPSxe2x80x9d) mode, Multi-domain Vertical Alignment (hereinafter referred to simply as xe2x80x9cMVAxe2x80x9d) mode or the like has been known; however, even these have not secured a viewing angle wide enough for the monochromatic images, especially for the medical application.
On the other hand, as an LCD which can obtain a preferable contrast ratio over a wide viewing angle, a method has been known in which collimated light (parallel light) is used as backlight (collimated backlight) as well as light transmitted through a liquid crystal panel is diffused by a diffusion plate.
However, any LCD which attained a viewing angle wide enough for the medical application using the diffusion plate has yet to be realized. The method using the diffusion plate has a problem that external light or extraneous light incident on the diffusion plate is reflected as well as diffused; therefore, the contrast of a viewed image is decreased; as a result, an appropriate image can not be viewed in many cases.
As is seen in the LCD, a highly precise display in which not only a matrix structure of digital pixels is clear, but also sharpness is high, is appropriate for representing artificial images such as Computer Graphics (hereinafter referred to simply as xe2x80x9cCGxe2x80x9d).
However, there is a problem that LCD has the matrix structure of digital pixels so that clearness of this matrix structure contradictorily provides a mosaic impression to a still image, such as an X-ray image, which has natural smoothness whereupon an improper appearance in which the image is jagged, namely, pixelization (or jaggy) occurs. When an image size is large (for example, about 300 xcexcm in 15xe2x80x3XGA (Extended Graphics Array)), this problem becomes particularly conspicuous since vertical stripes of a matrix structure of a color filter are clearly seen.
Moreover, this problem is not limited to LCD, but the pixelization occurs in a color CRT, a Plasma Display Panel (hereinafter referred to simply as xe2x80x9cPDPxe2x80x9d) or the like as long as they have a matrix structure.
A first object of the present invention is to solve the above-described problems of known prior arts and to provide a light diffusing plate which has an excellent light diffusing efficiency, and can preferably reduce a contrast drop to be caused by a surface reflection, keep a satisfactory contrast ratio over a wide viewing angle when applied to a liquid crystal display and realize the liquid crystal display preferably applicable to a medical use, and a display apparatus for the liquid crystal display device, which employs this light diffusing plate.
A second object of the present invention is to solve the above-described problems of known art and to provide an image display apparatus which can eliminate pixelization (jaggy), namely, perform depixelization and obtain a smooth, natural displayed image.
In order to attain the first objects described above, the first aspect of the present invention provides a light diffusing plate comprising: an unrecognizable structure which has an optical refractive power; passing areas through which a collimated light incident from a side of the unrecognizable structure passes; and a non-passing area other than the passing areas, which has relatively low light transmissivity compared with the passing areas; wherein materials of the passing areas and non-passing area are applied simultaneously.
It is preferable that the light diffusing plate comprises a light transmitting support and a diffusing layer formed on the light transmitting support by fixing light transmitting spheres which constitute the passing areas to the light transmitting support with a light absorptive binder which constitutes the non-passing area.
The present invention provides a light diffusing plate, comprising: a light transmitting support; a diffusing layer having light transmitting spheres; and a light-sensitive thermal developing material layer which is formed between the light transmitting support and the diffusing layer; wherein the light-sensitive thermal developing material layer contains a light-sensitive thermal developing material which forms no color in an exposed areas; and wherein the light-sensitive thermal developing material is heated to form a color after nearly collimated light is incident from the diffusing layer side.
The present invention provides a light diffusing plate comprising: a light transmitting support; a diffusing layer having light transmitting spheres; and a thermal ablative layer formed between the light transmitting support and the diffusing layer. Wherein the thermal ablative layer which contains a light absorptive thermal ablative material, in an area which is illuminated by a nearly collimated light incident from a side of the diffusing layer, is removed by thermal energy by means of the nearly collimated light.
The present invention provides a light diffusing plate comprising: a light transmitting support; a diffusing layer containing light transmitting spheres; and a contacting material which contacts the light transmitting spheres; wherein the contacting material contains a light-sensitive material which forms no color in an exposed area and a light absorptive material; and wherein the light-sensitive material is heated and developed to form a color after nearly collimated light is incident from a side of the diffusing layer.
The present invention provides a light diffusing plate comprising: a light transmitting support; a diffusing layer containing light transmitting spheres; a contacting material which contacts the light transmitting spheres and contains a light absorptive material; and a light-sensitive material which forms no color in an exposed area and is provided between the contacting material and the light transmitting support; wherein the light-sensitive material is heated and developed to form a color after nearly collimated light is incident from a side of the diffusing layer.
It is preferable that the diffusing layer is formed by forming a layer of the contacting material previously and then embedding the light transmitting spheres into the layer of the contacting material.
It is also preferable that a surface of a side opposite to the diffusing layer in the light transmitting support is treated with light non-reflection processing.
In order to attain the first object described above, the second aspect of the present invention provides a display apparatus comprising: a liquid crystal display panel; a backlight unit which forces a collimated light to be incident on the liquid crystal display panel; and a light diffusing plate which is located in an opposite side of the backlight unit against the liquid crystal display panel; wherein the light diffusing plate comprises an unrecognizable structure which has an optical refractive power, passing areas through which a collimated light incident from a side of the unrecognizable structure passes, and a non-passing area other than the passing areas, which has relatively low light transmissivity compared with the passing areas; and wherein materials of the passing areas and non-passing area axe applied simultaneously.
The present invention provides a display apparatus comprising: a liquid crystal display panel; a backlight unit which forces a collimated light to be incident on the liquid crystal display panel; and a light diffusing plate which is located in an opposite side of the backlight unit against the liquid crystal display panel; wherein the light diffusing plate comprises a light transmitting support, a diffusing layer having light transmitting spheres, and a light-sensitive thermal developing material layer which is formed between the light transmitting support and the diffusing layer; wherein the light-sensitive thermal developing material layer contains a light-sensitive thermal developing material which forms no color in an exposed area; and wherein the light-sensitive thermal developing material is heated to form a color after nearly collimated light is incident from the diffusing layer side.
The present invention provides a display apparatus comprising: a liquid crystal display panel; a backlight unit which forces a collimated light to be incident on the liquid crystal display panel; and a light diffusing plate which is located in an opposite side of the backlight unit against the liquid crystal display panel; wherein the light diffusing plate comprises a light transmitting support, a diffusing layer having light transmitting spheres, and a thermal ablative layer formed between the light transmitting support and the diffusing layer; wherein the thermal ablative layer which contains a light absorptive thermal ablative material; and wherein the thermal ablative material in an area which is illuminated by a nearly collimated light incident from a side of the diffusing layer is removed by thermal energy by means of the nearly collimated light.
The present invention provides a display apparatus comprising: a liquid crystal display panel; a backlight unit which forces a collimated light to be incident on the liquid crystal display panel; and a light diffusing plate which is located in an opposite side of the backlight unit against the liquid crystal display panel; wherein the light diffusing plate comprises a light transmitting support, a diffusing layer containing a light transmitting spheres, and a contacting material which contacts the light transmitting spheres; wherein the contacting material contains a light-sensitive material which forms no color in an exposed area and a light absorptive material; and wherein the light-sensitive material is heated and developed to form a color after nearly collimated light is incident from a side of the diffusing layer.
The present invention provides a display apparatus comprising: a liquid crystal display panel; a backlight unit which forces a collimated light to be incident on the liquid crystal display panel; and a light diffusing plate which is located in an opposite side of the backlight unit against the liquid crystal display panel; wherein the light diffusing plate comprises a light transmitting support, a diffusing layer containing light transmitting spheres, a contacting material which contacts the light transmitting spheres and contains a light absorptive material, and a light-sensitive material which forms no color in an exposed area and is provided between the contacting material and the light transmitting support; and wherein the light-sensitive material is heated and developed to form a color after nearly collimated light is incident from a side of the diffusing layer.
It is preferable that the display apparatus further comprises a preventing sheet for preventing from scattering an extraneous light wherein the preventing sheet is provided on the light diffusing plate which was provided on a viewing side of a display screen of the liquid crystal display panel.
In order to attain the third object described above, the third aspect of the present invention provides an image display apparatus comprising: an image display device having a matrix structure; and a light diffusing plate comprising: an unrecognizable structure which has an optical refractive power; passing areas through which a collimated light incident from a side of the unrecognizable structure passes; and a non-passing area other than the passing areas, which has relatively low light transmissivity compared with the passing areas, wherein materials of the passing areas and non-passing area are applied simultaneously, and wherein the light diffusing plate is provided on a viewing side of a display screen of the image display device.
It is preferable that the light diffusing plate comprises a light transmitting support and a diffusing layer formed by fixing light transmitting spheres with a binder on the light transmitting support.
It is also preferable that the image display apparatus further comprises a preventing sheet for preventing from scattering an extraneous light; wherein the preventing sheet is provided on the light diffusing plate which was provided on the viewing side of the display screen.
The present invention provides an image display apparatus comprising: an image display device having a matrix structure; and a light diffusing plate comprising an unrecognizable structure which has an optical refractive power; wherein the light diffusing plate is provided on a viewing side of a display screen of the image display device.
It is preferable that the light diffusing plate comprises a light transmitting support and a diffusing layer formed by fixing light transmitting spheres with a binder on the light transmitting support.
It is also preferable that the image display apparatus further comprises a preventing sheet for preventing from scattering an extraneous light; wherein the preventing sheet is provided on the light diffusing plate which was provided on the viewing side of the display screen.